Cement is made up of calcium, aluminium, silicon and iron the source of these being limestone, clay and sand. The mix of all the above is grinded with more than three fourth limestone, and pre-heated. It is then heated up to 1400 degree centigrade in a rotating furnace kiln, where decarbonation takes place, releasing carbon dioxide, slurry and clinkers. The clinkers are set into a horizontal chamber for final and fine grinding.
India is the second largest manufacturer of cement in the world with more than 360 million tonne annual capacity. The price of cement usually indicates the health of the economy and the rate of infrastructure development, and shift if monetary investments from real estate to others.
Cement has become popular due to the ease in use, flexibility and strength. So what are the drawbacks of using cement ? Cement deteriorates with age unlike limestone which stays stronger for years. Cement and concrete, hence, cannot last for more that 60 to 80 years. Manufacture of cement contributes to greenhouse gases as carbon dioxide is released in the process of manufacture.
Cement absorbs heat from the sun and cracks up while traditional building with stone, wood and non-homogeneous roofs do not crack up. Similarly cement cannot withstand even minor earthquakes. While we know the drawbacks of using cement, we continue to use extensively in construction and this is a dangerous trend. It is time to look outside of cement for better and more sustainable building materials.
SOURCE : The Hindu